Means for multiplying voltages



Filed Oct. 24, 1946 y 1949- v. M. cousms 2,471,262

MEANS FOR MULTIPLYING VOLTAGES 2 Sheets-Sheet 1 FIG! - CONTROLLER l I 2 CONTROLLED CU TPU T lNl/EN TOR M M. COUS/NS A T TORNEY y 1949- v. M. cousms 2,471,262

MEANS FOR MULTIPLYING VOLTAGES Filed Oct. 24, 1946 2 Sheets-Sheet 2 P OUTPUT OUTPUT INVENTOR 1 M. COUS/NS A T TORNEV Patented May 24, 1949 This invention-relates m vel-tage multipliers, voltage dividers, modulators and demodulators.

'lhe 'objct of the invention is electrical circuit producing a"voltage propmtional 'in: ampli- 3 tude to the product or quotient of the amplitudes oftwdgiven'vol'tags;

feature of "t "e "in *Anotheireatureb'r li' menacestpe aesigfn and dispositionflo f the tn- 6ntr'o11ed elements s5 that the" controlled eleirnents'ivvill have'sin ilarvariations with a yariation of the current in the controlling neme'rm; urient' in' 'controlling netic, mechanical I=or(;other:,= are-"wknown "inwhichst. the current in a controlling elementivcontrols r some electrical characteristics; two orzm'or controlled elementsl ""5 In a typical embodiment of the invention,--a source of a first signal voltage is connecte'd'to the input circuit of an amplifier, and the output circuit of the amplifier is connected to the controlling element. The first controlled element is so connected to the amplifier as to control the output voltage ,of the amplifier by supplying a voltage whi'clropposes the" first signaljvoltagew The'system' -will stabilize itself when some electrical property of the controlled element has been changed =bythe current inthe controlling lement r s f ne li tb a am wl o h firsfilsigini l voltage. A similar changeis zproduce d in a .char a acteristic of the second controlled elernent. A source ofagsecond signalvoltage isconnectedtto a circuit so arranged that the transmission equivletat of: this a. c r ui hegc rr ntt fr m; th

second signal source is controlled;by1thegsecond controlled, element;- The output voltage of: this: second circuit-will-thenbe proportional in=a1np1i'- tude to theiproduct or quotientcftheamplitud v V. 1; 5;, H 2,471,232?

EOlt MUL rIPLYIfNG para-pha 'Vention is "the combination of ari= airiplitler a: controlling element and 'a"'iir's't controlled? eminent "cpimectea r gin loop irca-iv; and a scond'elmen controlled by said'control ,hem iiq g a m York, N. YQ, acorporation ofNew -Y v np neanomocmper 2 voltage ,ez is con the input circuit of t p I the-voltage supplied v t the. tim cu it' inc ding thes ces is constant. Let the current in the load 9 be ii,

then, if the impedance b'ftheioad 9 is small, compared to that of element a d'aja'nr v the load, are proportional to the product of the amplitudes of the voltagesj le ez divided by the amplitude of the voltage eaif to 'a loa'd. ircuit a; p r ugh. the impede} "1th the source '1 5 ,s'uppl iedilto the E theyoltage cross; theiinput :1 4 Fe ced ia n li i le flowing in;the;-series cirwe ojltage across The voltages from the sources 6 and 1 should be of the same kind, but opposite polarity; that is, the voltages may both be unidirectional but of opposite polarity, or both alternating, of the same frequency but opposite phase. The voltage from the source 8 may be of any kind or polarity.

In Fig. 1, since the controlling element 4 is equally afiected by: currents of either polarity, if the voltage supplied to the input circuit of the amplifier by the source I exceeds the voltage supplied by the source 6, the source .1 will tak control, causing the element 4 to -increase-"the admittance of element 3 until the'output current is limited only by the overload current 'oi'-the-amplifier, or the failure of some elementid'the'cir cuit. This effect may be avoided by the circuit shown in Figs. 2 and 2A, inwhich"elements" which correspond to the elements of Fig.1, have the same reference characters.

In Fig. 2, .a sourceof voltage is connected through a resistor I tothe input circuit of'an amplifier 5. The source 6 is symbolic ofany voltage source which is arbitrarily. varied, and may be replaced byany such sourceof variable voltage. v

A source of biasingwoltage .L'of the saniekind but opposite polarityto the .voltage. from the source 6,'is connected through the .bead.3 of an indirectly heated thermistor to the input circuit of amplifier 5."

The output circuit of 'amplifieri'is' connected to ground through.acunilaterallyconductive device l2 and the heater 4 'otthe thermistor.

A source-of voltage 8 isconnected througha second bead 2 of the thermistor to'the input 'cirlcuit of a second amplifir lflhavingla feedback resistor 9.

The amplifier l0 .may be of the type shbwnin United StatesPatent"2;401','779;June ll, 1946, K. D. Swartzel; Jr.', though'oth'er'high gain'stable amplifiers, having suitable" response-frequency characteristics,mayibe used;'

The source '1, elements 3,1 'and'thevoltage applied by the source "6 arein series. Let thevoltages supplied by the'sourcelfiand source"! be 61, ex and the admittances'of "elements 1, the A1, in. Assume that initially? so that a net excess voltage -from"source 6 will be applied to theinputcircuitor amplifier" 5 i which will causea current to 1l6winthe heater 4 which will increase the admittance of th bead 3, and this action will continue until the net voltage applied to the input circuit of the amplifier is just sufiicient to maintain the required current in the heater 4.

If the output voltage required to maintain this current is say 50 volts, and the voltage amplification of' the-amplifier is say 50;00O,"the net'voltage applied to the input-circuit oramplifier 5'? need only be .001 volt,"and mayb'e ignored? Let the current flowing in elements I, 3 be i, then if the voltage across the input" circuit is ignored, as before The beads 2, fofththefmistor are sym- Then,

The output voltage of amplifier ID has an amplitude'proportional to the product of the amplitudes of the voltages applied by the sources 6 and 8.

Fig. 2A is identical with Fig. 1, except that the elements 2 and 9 have been interchanged.

Then

In this case the output voltage is proportional to the quotient of the amplitudesof the applied voltages.-

To prevent the runaway action-found in the simplecircuit of Fig. 1, a-unilaterally conductive element I2, such as a diode, copper-copper oxide couple, grid controlled or otherrectifier, may be connected in the circuit to-the heater 4, 50 that current is only supplied to the heater 4 when the voltage at the input of amplifier 5 from the source 6 exceeds the voltage from the sourcel.

If the voltage from the source 6 is alternating, theelement I2 should be a device, such as a grid controlled. rectifier in which the conduction period is controlled by the phase of the voltage from the source 6. A similar efiect may be securedby arranging the output'circuit of amplifier 5 so-that only voltage of the proper polarity is supplied by the output circuit.

Fig. 3 is similar to Fig. 2 except that the device l2 and source! have been removed, and the bead 3 connected as a feedback resistor fromthe output to the input of amplifier 5.

Let

er be the voltage of the source 6 :e: the voltage of the source 8 ea the output voltageof amplifier 5 -:eo the output voltage of amplifier IO The circuits of Figs. 2, 2A, 3,-3A give output 'ivoltages proportional in magnitude to the product or quotient of er and ex, but the polarity or sign of the product orquotient is determined only by the polarity or sign of the voltage er; the amplitude of the voltageei being a mere multiplier or divisor.

Fig. 4 is generally similarto-Fig. 2, and elements having similar functions are designated by the same reference characteristics; but a source ll of voltage cm, of opposite polarity to the source I is connected through resistor l2, having an admittance A12, to the input circuit of amplifier 5 to bias the thermistor to the center of the operating range.

The output voltage 610 of amplifier Ill will be Let the voltage of the source H be initially so selected that, when the voltage $61 from source 6 is zero, the zero signal admittance A20 of the bead 2 equals KA1, then,

8 (5: 2) (i2 1) KA1 2) 12) 20] m a e 3 9 The output circuit of amplifier I is connected through resistor l3, to the input circuit of a unity gain amplifier l6, having a feedback resistor I l. The source 8 is connected through resistor l having the same resistance as resistors l3, It, to the input circuit of amplifier l6. Let the resistor 9 be selected so that its admittance Then, the output voltage cc of the amplifier IE The amplitude of the output voltage 60 is proportional to the product of the amplitudes of the voltages 6162 and the polarity or phase of the out put voltage an is that of the algebraic product (1261) (1'62) The voltage em from the source I! may also be varied in amplitude so that the output voltage en is proportional to the product of the amplitudes of the voltages e1, e2, divided by the amplitude of the voltage era. In this case, as in Figs. 2, 2 -A, a unilaterally conductive device H is connected in series with the heater i.

A plurality of beads, such as the bead 2, may be associated with the heater 4. Independent sources of voltages, similar to the source 8, may be connected to these beads, or to input resistors corresponding to resistor 9, producing an output voltage of the form ier (iez, ies, etc.) or the corresponding quotient.

Fixed resistors may be associated with the elements of the thermistor to modify the characteristics of these elements, to improve the performance of the circuit, or to produce desired functional variations in the amplitudes of the voltages.

In Fig. 5 a source 6 of a voltage e1 is connected through a resistor l having an admittance A1, to the input circuit of a high gain amplifier 5. A feedback resistor 2, having an admittance A2 is connected from the output to the input of amplifier 5. A second source 1 of a voltage +ea is connected through the bead 3 of a thermistor, having an admittance A3 to the input circuit of the amplifier 5. A filter 9 in series with the heater 4 of the thermistor is connected across the output circuit of the amplifier 5. The output circuit of the amplifier 5 is connected through a filter H] to the output terminal II; the common grounded connection of the input and output circuits being connected to the output terminal l2.

The filter 9 has a, transmission characteristic which will pass the current from the source 6 and source 1.

Let a source 8 of a voltage as be connected in series with the source I, and the filter 10 have a transmission characteristic which will pass the current from the source 8 and reject the current from the sources 6 and 1.

The current i1 from the source 6 equals ezAr and the current is from the source 1 equals 63A3, and as only currents of this type are passed by the filter 9 to the heater, when the system is balanced,

The filter l0 passes only currents from the source 8, thus, the output voltage The voltages eies from the sources 6 and I are of the same kind, but of opposite polarity or phase, are passed by the filter 9 and rejected by the filter Ill. The voltage ez from the source 8 is of different kind, is passed by the filter l0 and rejected by the filter 9.

If e1 is a varying unidirectional voltage, 63 a constant unidirectional voltage of opposite polarity, and c2 an alternating voltage of constant amplitude, the output voltage e0 will be an alternating voltage, of the frequency of ca, but varying in amplitude with the variations of (21. If ez is an alternating voltage of varying amplitude, then e0 will be an alternating voltage, of the frequency of e2, but varying in amplitude with the product of the amplitudes of e1 and e2. The circuit thus operates as a modulator. Similarly, er and ex may be alternating voltages of one frequency but opposite phases and 62 may be an alternating voltage of different frequency.

On the other hand, the voltages 6163 from the sources 6 and I may be alternating voltages of the same frequency but opposite phases, and the voltage e2 from the source 8 may be a unidirectional voltage. The circuit will then operate as a demodulator.

What is claimed is:

1. An amplifier having an input and an output circuit, a device having a controlling element connected across said output circuit and at least one controlled element, two sources of voltages of opposite polarity, an impedance connected in serial relationship with said controlled element to the tree poles of said sources, and a connection from the junction of said impedance and said controlled element to the input circuit of said amplifier, whereby the characteristics of said controlled element are varied proportionally with the voltages from said sources.

2. The combination in claim 1 with a source of a. third voltage, a load, and a second element controlled by said controlling element so that the ratio of the admittances of said controlled elements is substantially constant connected from the source of said third voltage to said load.

3. A high gain amplifier having an input and an output circuit, a thermistor having a heatin element connected across said output circuit and at least one bead, two sources of voltages of opposite polarity, a resistor connected in serial relationship with said bead to the free poles of said sources, and a connection from the junction of said resistor and said bead to said input circuit.

4. The combination in claim 3 with a source of a third voltage, a. load, and a second bead of said thermistor controlled by said heating element so that the ratio of the admittances of said two beads is substantially constant connected from the source of said third voltage to said load.

5. The combination in claim 3 with a unilaterally conductive device in series with said heating element, a. second amplifier having a second input and a second output circuit, a source of a third voltage, a second resistor, a second bead of said thermistor, said source of a third voltage, second resistor and second bead being connected in serial relationship across said second output circuit, and a connection from the junction of said second resistor and second bead to said second input circuit.

6. A first amplifier having an input and an output circuit, a unilaterally conductive device, a thermistor having a heater connected in serial relationship with said device across said output circuit and two beads, two sources of unidirectional voltages of opposite polarity, a first resistor connected in serial relationship with one of said beads to the free poles or" said sources, a connection from the junction of said resistor and head to said input circuit, a second amplifier having a second input and second output circuit, a third source of voltage, a second resistor, said third source, second resistor and second bead being connected in serial relationship across said second output circuit, and a connection from the junction of said second resistor and head to said second input circuit.

'7. The combination in claim 6 in which said second resistor is connected from said second output circuit to said second input circuit.

8. A first amplifier having an input and an output circuit, a thermistor having a heater con-- nected across said output circuit and two beads, two sources of unidirectional voltages of opposite polarity, a resistor connected in serial relationship with one of said beads to the free poles of said sources, a connection from the junction of said resistor and bead to said input circuit, a first source of signal voltage, a second resistor connected from said first source of signal voltage to said input circuit, a second amplifier having an input and an output circuit, a second source of signal voltage, a third resistor connected in serial relationship with the second bead of said thermistor and said second source of signal voltage across said second output circuit, the junction of said third resistor and bead being connected to said second input circuit, a third amplifier havin an input and an output circuit, a fourth resistor connected from the output to the input circuit of said third amplifier, a fifth resistor connected from the output circuit of said second amplifier to the input circuit of said third amplifier, and a sixth resistor connected from said second source of signal voltage to the input circuit of said third amplifier.

VAN M. COUSINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,084,135 Ford June 15, 1937 2,098,968 Mallinckrodt Nov. 16, 1937 

